Oscillograph galvanometer



Jan. l, 1929.

J. W. LEGG OS C ILLOGRAPH GALVANOMETER ATTORNEY Jan. l, 1929. 1,697,191

J. w. LEGG OSCILLOGRAPH GALVANOMETER Filed Jan. 12, 1925 2 Sheets-Sheet2 ATTRNEY ,Patented Jan. 1, 1929.

UNITED y STATES PATENT OFFICE.

JOSEPH W. LEGG, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A. CORPORATION OF PENNSYLVANIA.

OSCILLOGRAPH GALVANOMETER.

My invention relates to galvanometers and particularly to galvanometersadapted for service in osci'llographs.

One object of m invention is to provide a device of the a ove indicatedcharacter that shall be extremely compact in construction and effectivein operation.

Another object of my invention is to provide a galvanometer subject torelatively high voltages that shall be adequately protected and that maybe easily and safely manipulated.

Figure 1 of the accompanying drawing is a plan v1ew of a galvanometer.embodying` my invention,

Figure 2 is a view taken partially in end elevation and partially alongthe line II-II of Fig. 1, I

Fig. 3 is a front view, partially in section and partially in elevation,4of a portion of the device shown in Fig. 1,

Fig. 4 is an enlarged cross-sectional view of a well structure,constituting part of my invention, taken at right angles to thestructure shown in Fig. 3,

Fig. 5 is a detail view taken' at right angles to Fig. 4 and f Fig. 6 isa detail view of one member of the device.

A main insulating supporting 'structure comprises a horizontal baseplate or member l, vertical plates 2 disposed adjacent to the endsthereof, an intermediate vertical late 3 extending between the inneredges o the end plates 2 and `relatively short vertical partition platesor members 4 extending from the intermediate plate 3 to one side edge ofthe base plate. The construction described above divides the supportingstructure into a relatively large compartment in` which a coil 5 is disosed and three smaller compartments'in whlch well structures 6 areydisposed. y

A cylindrical magnetizable c re member 7 extends through the oil- 5 andVhrough the end plates 2 and is provided at its endswith horizontal yokemembers 8 that extend forwardly to positions opposite a'centerjlinethrough the well structure 6. Nutsf9 secure the yoke members 8 to. thecore memberf(y and longitudinal rods or ,bars-10 serve to holdthevertical plates together. l

Each' of the plates 4, as shown more clear-A ly in Figs. 3 and 5, ispreferably built up of a pluralit of relatively thin layers of paper, orotliier suit-able material, having central recesses for the reception ofa pair of magnetizable disks or pole members 12 and central layers 14which extend between, and beyond the edges of the members 12. The latterare provided with flanges 15 serving to enlarge the adjacent facesthereof and to better anchor the members in the paper layers,constitutin the partition, which are impregnated wlth a binder andhardened under heat and pressure. This" construction provides a singleseries magj netic path for all of the well structures 6 comprising thecore member 7, the yoke members 8 and the pole members'12. The 70 thinpartitions 14- permit the passage of -magnetic flux but, with the otherinsulating parts, prevent short circuiting between independent circuitsof theseveral well structures which are hereinafter set forth. The yokemembers 8.are provided with openings for the reception of screws 17 thatextend therethrough. The pole members 12 are provided with trunnionportions 19.

Eachwell structure 6 comprises a cylinso drical cupU member 20,preferably of nonmagnetic, non-corrosive material, such as moldedinsulating composition, having a top opening 21, side openings 23, afront opening 24 and a bottom opening 25, the-latter 85 of whichconstitutes a drain outlet normally closed-by a screw or plug 26. Theside openings 23 are adapted for the reception of transverse op.ositely` alined pole members 28 having re uced inner end 90 portions -29and laterallyexpanded or discoid'a'l oter end portions 30 for co-opera-yvtive engagement with the outer surfaces'of thel pole members 12 in theplates 4. The l outer` surfaces of thej outer end portions 30 '95 areprovided with grooves 32 and 33, as shown in Fig. 2, whereby the wellstructures may be inserted into operative position between the plates 4.In effecting such inser-4 tion, the well structures are lowered while inum slightly laterally offset, position relative to the final "positionsthereof tb pass the grooved portions 32 over the trunnions 19, afterwhich the gfrooved portions 33` are t moved horizontally to place the'trunnions'lo; l

1 9 in the rear endl of the grooves 33.

c provided with openings 42 therein and forwardly projecting portions 43having upper bearing surfaces 44 and front edge flanges 45.

`lletal structures 47 adapted for the support of vibrating elements 48are mounted in fluid-tight relation on the cover members 39, inengagement with the bearing surfaces 44 and are provided with dependingportions 50 upon which'the elements 48 are mounted.

The structures 47 are yieldably held in position against the surfaces 44by screws 51, that extend through bosses 52, and resilient washers 53disposed between the heads of the screws 51 and the outer ends of thebosses Segmental gear` members 55, secured tothe structures 47co-operate with pinions 56 for adjusting the-- vibrating elements 48angularly about the longitudinal axis of the cup `members 20. Thepinions 56V are mounted in the cover members 39 through shafts 59 thatare provided with insulating handles 60. ."2

Guide or supporting members 62, preferably of ivory are provided for theelements 48, and are secured to the depending portions 50 by screws 63.

Each vibratory element 48, preferably pf flat strap construction,extends from `a member 65, grounded to the portion 50, over the ivoryguides 62, a ulley or roller 66 and from the pulley 66 ack over theguides 62 to a conductor 68.. The latter extends through an insulatingbushing 69 in the portion 5() to aterminal device 7 0 whicli'constitutesone terminal of the element 48 and is insulated from the metal structure47 by a bushing 71. A similar terminal device 72, constitutlng the otherterminal of the elenient 48 is grounded to the metal structure 47 by ascrew 73. The above construction provides two strands of the elementt 48between the guides 62 disposed in parallel sideby-side relation slightly.spacedapart.A A` mirror is mounted on the element opposite the frontopening 24 in the cup member 20. The opening 24 is sealed by a glassplate 7 6' which is inclined slightly to prevent reflections from a beamof light that isL ladapted, to enter an opening 77 in the memj ber 35being projected normal to the surface of the mirror 75. The member 35 isalso cupped or depressed to similarly prevent refiections beingprojected normal tothe Isurface of the miror 75.

The pulley 6.6 is mounted at oneend of a l member 8l) that is centrallypivoted, bya pin 81, betweenv depending portions 82 of the portion 50. Avertically disposed helical spring 83 is secured, at its lower end, tothe other end of the member 80, by a pin 84, and, at its upper end, toan adjustable screw 86 that is mounted in anenlarged portion 87 of themember 65 and is provided with a nut 88.

In mounting the element 48, the member 8() is initially moved slightlyclockwise from the position shown in lFig. 4 against the action of thespring 83 and wedged in such position, as by placing a splint betweenthe member and the portion 82. This operation raises the pulley 66slightly. The element 4S is then, securedfto one of the members 65 or68, as by soldering, and

brought down over the guides 62 and around the pulley 66. The element isthen drawn upwardly, Yunder slight tension over the guides 62 andsimilarly secured to the other member 65 or 68. When the wedge iswithdrawn to release the member 80, the latter will be movedcounter-clockwise by spring 83 to place the element 48 under the desiredtension.

The pin 81 being at the center of the member 80 there will be notendency for the latter to be displaced relative to the portion 50 whenthe latter is jarred. Thus when the device is subjected to -vibration orjarring,

the element 4 8 will be under no fracturing stresses other than thosecaused by its own inertia and, sincethe element is extremely light inweight as compared to its tensile strength, it is ractically proofagainst damage from such auses. j

As shown m re clearly in Fig. 1, the reduced inner ends of the pole..members 28 are sloped from rear to front to provide adjacentconcentrated lpoles between which the vibrating element 48 extends. Thespace, at the rear ofthe pole membersf28'thus provided` is occupied vbythe port-ionr50 and t-he spring 83. i i

In mounting the structure 47, the portion 50 with the element 48 andtheaccompanying partsi'sr lowered through the opening 42 `along averticalline that is displaced to the `in Fig. 4, until the forward edgethereof engages the flanges 45 on theprojection 43. This action bringsthe screw.51 into register with an opening therefor in the member 39,

after which the-pinion 56 and its handle 60 are placed in position. j

An adjusting rod or bar 90, see Figsi 1 and 2,..i's "provided at itsupper and lower ends, with right-hand and 'left-hand screwthreadedportions 91- `and 92,' respectively,

and also has a handle portion 94.- The porand the coil 5 is connectedtoa small directcurrent source (not shown) to energize' the core member 7,the yoke members 8 and the pole lmembers 12 and 28. The members 7, 8,and 12 constitute a single series magnetic circuit having air gapsbetween the reducedv ends of the pole members 30 in which are disposedthe vibratory elements 48. The latter are adapted to be connected to acircuit to be tested through the binding posts 70 and 72 and, whenenergized, react with the magnetic field between the pole members 30 tocause the mirrors 75 to vibrate, the instantaneous deflection of themirror' being proportional to the instantaneous value of the currentbeing studied.

Light beams are directed through prisms,

according to the usual practice` through the openings 77, to thevibratory mirrors 75 and, from the latter, back through 4the openings 77to a photographic film or other device for observation of the circuitunder test.

Since it is desirable to direct concentrated beams or pencils of light'and to avoid ineidental reflection, the glass plate 76 is inclined andthe member 35 is cupped or curved inwardly at its outer surface torender the surfaces of the mirrors the only surfaces normal to saidbeams. To further insure the absence of reection, the surfaces of allparts other than the surfaces of the mirror are rendered as nearlyreflection :proof as practicable.

The elevation of ,the reflected light beams from the mirror 75 to thephotographic films may be adjusted "5y manipulation of the handles 94.Turning of these handles by reason of the right-hand and left-handscrew-threaded portions 91 and 92, respectively, on the rod 90, tiltsthe cup members 20 to Iany desired angle.

The light beams may be adjusted laterally by vturning the handles 60,which Inovement turns the pinions 56 and, consequently, the gearsegments 55 and the vibrating elements 48. y

Damping of the elements 48 is effected by bodies of suitable Huid (notshown)4 which the cup members 20are adapted to receive through the top'openings 21 thereof. The bottom openings 25 permit draining of thecup-members 20. Since the metal structures 47 are mounted in fluid-tightrelation tothe stead of a separate coil for each flux gap,

and economy of space obtained to a high degree. This feature isespecially useful in obtaining a readily portable device, such as anoscillograph, where the previous devices have been many times larger andheavier and have not been portable in the sense that a single personcould carry them.

Further, the particular method of mounting the vibratory elementswhereby the elements are not readily broken is particularly desirablebecause such elements have heretofore been a great source of annoyancefrom this cause.

While I have shown and described aparticular form of my invention,changes may be effected therein without departing from the spirit andscope thereof, as set forth in the appended claims.

I claim as my'inve'ntion:

1. An instrument comprising a magnetizable core member, a pair of polemembers, disposed in series magnetic flux-path rela tion thereto, meansdisposed in a gap betwcen said pole members for co-operation i with themagnetic field therebetween and a body of laminated insulating materialconstituting a partition between one of said pole members and said coremember,

2. An instrument comprising a magnetizable core member, 'a pair of polemembers, disposed in series magnetic iiuX path relation thereto, meansdisposed in a gap between said pole members for co-operation with the maetic field therebetween and a body of lamlnated insulating materialconstituting a partition between one of said pole members and said coremember, said body having an intermediate imperforate sheet or sheetsextending laterally over and beyond the end of the pole member and aperforate sheet or sheets secured to said imperforate sheet or sheets tothicken the partition outside the metallic flux path.

3. In an instrument, the combination with a fiux responsive element, ofa magnetic flux path structure having a fiuX gap in hich said element isdisposed and includi/lfg two magnetizable members having adjacentperimetrally flanged end portions and a body of insulating materialhaving a portion constituting a partition between saidv endportions anda portion surrounding said partltion and said flanges to assist inholding said members together.

4. A galvanometer comprising a plurality of pairs of series-relatedmagnetic lpole members, a vibratory element in a gap between each pair,a pair of ,spaced magnetiz/able members between each pair of polemembers,

and an insulating structure surrounding,^andl disposed between saidspaced magnetlzable members, said insulating structure being constructedof a'plurality of superposed layers of insulating material boundtogether to constitute a single rigid structure.

5. A Agalvanometer .comprising 'a well structure, magnetic pole membersprogectin'g inwardly from opposite sides, thereo a vibrating elementbfor vertical disposition in the well between the pole members, aremovable supporting structure for vthe element, said structures beingconstructed and related yto permit the element to be freely placed inthe well and withdrawn therefrom in the direction of the longitudinalaxis of the well along a path laterally removed from said pole membersand to be moved transversely to and from position between the polemembers, means for limiting said transverse movementto position'theelement in predetermined relation to the pole members, and means foraccurately guiding the element into position in said well.

6. A galvanometer comprising a well structure having an opening in aside wall thereof, a vibratory element vertically disposed in the well,a mirror carried by the element opposite and facing said opening, and areflection shield for said opening having a curved-wall portion ofsubstantial cupshape bowed toward said mirror and a central openingopposite the mirror.

7. galvanometer comprising a supporting structure, a well structurehaving a light-transmittnig ,openingv therethrough and pivotally mountedon said supportin structure, and a member for holding sai well structurein operative position on said supporting structure 'and havin areflection-shield portion adjacent toy said opening. 8. A galvanometercomprising a well structure having a top bearing surface, a vibratoryelement, a supporting member for the element having a portion projectinginto the well and a transverse portion engaging saidbearing surface forangular slidable movement thereon and meansfor vertically yieldablysecuring said transverse portion in position on said surface.

9. In a galvanometer, the combination with a. pair of spaced parallelpartition members and a substantially vertical 4well member disposedtherebetween, of a bearing structure between each partition and theadjacent side of the well member comprising a trunnion extending;transversely to the longitudinal axis of the well, and a trunnionbearing member having a transverse groove, said bearing `structurepermitting the well member to be moved to and from pivoted positionbetween said partition members.

10. A galvanometer comprising a fluidtight Wellv structure for thereception of a liquid medium, a plate-like member movably mounted influid-tight relation to the top of and substantially overlying said wellstructure, a member projecting from said platelike member into said wellstructure, and a vibratory element mounted on said projecting member.

In testimony whereof, I have hereunto subscribed my name this 18th dayof December 1922..

/jJosEPH w. Lese.

